Warning: This post is full of pictures to help get my point across.
This is an aquarium light hood:
At homedepot they sell bulbs that look like this:
You already have a 15 watt bulb just like the one shown above in your hood. You can only put a 15 watt bulb or lower watt in your hood. To get more watts, you need to upgrade the light fixture. You can either get a new light fixture (read: not just the bulb) or modify your current one. You could put some sort of strip light fixture above your tank, like this:
(cheap and sold at homedepot)
Or something fancy like this:
(Generally expensive and sold at an LFS or online) Looks like this on your aquarium:
These above choices will replace your current hood.
To keep your existing hood, you can take out the current light fixture inside and replace with CFL bulbs. The new fixture sockets and lights can all be found at homedepot for cheap. They look something like this:
And will look like this when you put them in your hood:
But you don't have to upgrade your lights. You can have a beautiful planted tank with your existing lights. Here's a photo of mine (which is not beautiful lol, just a bad example
This is an aquarium light hood:
At homedepot they sell bulbs that look like this:
You already have a 15 watt bulb just like the one shown above in your hood. You can only put a 15 watt bulb or lower watt in your hood. To get more watts, you need to upgrade the light fixture. You can either get a new light fixture (read: not just the bulb) or modify your current one. You could put some sort of strip light fixture above your tank, like this:
Or something fancy like this:
(Generally expensive and sold at an LFS or online) Looks like this on your aquarium:
These above choices will replace your current hood.
To keep your existing hood, you can take out the current light fixture inside and replace with CFL bulbs. The new fixture sockets and lights can all be found at homedepot for cheap. They look something like this:
And will look like this when you put them in your hood:
But you don't have to upgrade your lights. You can have a beautiful planted tank with your existing lights. Here's a photo of mine (which is not beautiful lol, just a bad example